I am following the Agile Web Development with Rails 4 book and I'm a bit confused on a part about rendering. The simple version of the question is... within the application.html.erb file there it says
render @cart
This is confusing because I thought that there needed to be a controller associated with that view in order to know which partial and @cart variable to use. Is it simply by naming convention that this line looks for a partial like _cart.html.erb? And in that case does it not actually know what @cart is until it renders that partial?
Some clarification would be lovely. Thanks!
This is a shorthand syntax. From the docs:
Every partial also has a local variable with the same name as the partial (minus the underscore). You can pass an object in to this local variable via the :object option:
<%= render partial: "customer", object: @new_customer %>
Within the customer partial, the customer variable will refer to @new_customer from the parent view.
If you have an instance of a model to render into a partial, you can use a shorthand syntax:
<%= render @customer %>
Assuming that the @customer instance variable contains an instance of the Customer model, this will use _customer.html.erb to render it and will pass the local variable customer into the partial which will refer to the @customer instance variable in the parent view.
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